Photoflash casing



Nov. 9, 1943. R. LE R. KREIDLER 2,333,725

PHOTOFLASH CASING Filed ga 14, 1941 INVENTOR 1?. A 5/0; 5?. BY

ATTORNEY Patented Nov. 9, 1943.

' 2,333,725 ICE PHOTOFLASH CASING Raymond Le Roy Kreidler, Bloomfield,N. J., assignor to Westinghouse Electric & Manufacturing Company, EastPittsburgh, Pa., a corporation of Pennsylvania Application May 14, 1941,Serial No. 393,320

Claims.

M invention relates to photoflash lamps, and particularly to photoflashlamps having a casing of a plastic material.

An object of my invention is to provide a flash lamp of an organicplastic having efficient light output.

Another object of my invention is to provide a casing of an organicplastic capable of containing an active gas at more than atmosphericpressure. Another object of my invent-ionic to provide an easilyassembled photoflash lamp of an organic plastic casing not requiringtheapplication of high temperature.

Other objects and advantagesof the invention will become apparent fromthe following description and drawing in which:

Figure 1 is a front elevation of a preferred embodiment of my inventionsubstantially to its preferred actual scale.

Figure 2 is a cross sectional view on a much larger scale. I I

Figure 3 is a cross sectional view on lines III- III of Figure 2.

Figure 4 is an enlarged detail view of the interlocking joint betweenthe bulb and base in Figure 2.

Figure 5 is a cross sectional view illustrating the sealing of one ofthe conductors in Figure 2. Figure 6 is a view on lines VI-VI of Figure2 prior to the cutting off of the exhaust tube.

Figure 7 is a cross sectional view tion of the base of Figure 2.

My invention constitutes an improvement over the invention of aphotofiash lamp which is disclosed in the copending application ofMichael D. Margitta, filed January 26, 1940, Serial No.

My invention eliminatescompletely the problem of broken glass inconnection with the transportation, utilization and disposal ofphotoflash lamps by my choiceoi a plastic material. The preferredconstruction of my photoflash lamp proximately 40 mil material as thisis thin enough to be self-supporting and yet thick enough to moldproperly.

The preferred material is that of cellulose acetate although vinylcompounds, butyrates, methacrylates and similar materials may be used.This cylindrical portion preferably has a curved closed end H. The baseportion I? of the lamp is preferably of the same material and isdishshaped having an upper edge 13 with a recessed portion M to receivethe edge iii of the bulb portion I 0. The bulb portion lll preferablyhas a slight rounded rim 16 on its periphery near the edge l5 and thisprojecting rim i6 is adapted to be forced-into locking engagement with acorres ponding groove IT on the inner face of the recess M by the slightresiliency of the cellulose acetate wall l0. Theinterlocking jointbetween the bulb of a modificaedge l5 and the base rim l4 under thecompressed bulb edge l5 has a mechanical strength to prevent separationof the two portions under any increased pressure during flashingoperations.

The base has preferably a central depressed portion 20, from whichextends a central tubulation 2| for the purpose of exhausting andfilling the tube with an active gas such as oxygen. The lamp has twoconnections or standards 22 and 23, preferably of copper and bound inspaced relationship with each other by ahead of insulation 24 whichmaybe of glass or ceramic material, a tungsten filament 25,- and,preferably attached :theretafigniting means 26 and 21 formed by dippingthe conductors and filament into a nitro- -=cellulose binder containingpowdered zirconium,

.magnesium and potassium perchlorate.

The conductors 22" and 23 where they pass through the base arepreferably flattened as indicated at 28 in Figuresz and .5. Thebase hastwo integral tubular projections 29 surrounding this flattened portionof .the conductors. The conductorsare sealed to the projecting portions29 by having two preferably slightly heated flat also eliminates thenecessity of high temperatures during assemblage of the device. Myinvention also has the advantage that it permits the utilization ofoxygen inside of a photoflash lamp at greater than atmospheric pressure.With glass casing lamps at the prior art, there would be danger offlying particles of glass from the posslbility of explosion as theresult of the greater pressure of gas therein.

In Figure 1 I have disclosed an eievational view of my'photoflash lampin its preferred actual size. The structure ofthis .photofiash lamp'ismore clearly disclosed in Figure 2. The bulb portion H! is preferably aclosed end cylinder of an I organic plastic translucent to light andprefermetal surfaces 30 and3l, pinch the cellulose acetate projection 29about the flattened surface 28 of the conclucto'rs, as illustrated inFigures 5 and 6. The inner surface of the bulb and preferably also thebase. is sprayed with a .coating. 32 of a transparent inorganic material."that will not readily combine with oxygen zit-instantaneous htemperatures.

The material which we have found most suitable is that of sodiumsilicate. Other-"transparent inorganics that might be used are thosesold under the trade names of "Abapon and Stacol." The interior ofthe'bulb is then filled with a combustible metal suchas aluminum ormagnesium wire 33. :I prefer to use finely chopped aluminum foilhavingnacross sectional area ofl mil square;

The bulb. portion is then forced over the base and interlocked by therim l8 and groove II. A suitable cement 34 is then placed at theadjoining edges or the bulb and base portions, and this cement may becovered in turn it it is desired, by an additional lacquer coating 35.The interlocking joint takes all the strain and leaves to the cement andlacquer the sole job or making the joint vacuum tight. The atmosphere isthen removed from the lamp through the tubulation 2| and replaced withan active combustion supporting gas such as oxygen.

I prefer to insert oxygen at distinctly more than atmospheric pressure,and have found that a pressure of 120 to 150% of atmospheric pressureproduces a satisfactory flash in combination with the combustible metaland igniting means. In case higher pressures are desired, I increase thewall thickness of the bulb up to 100 mils or more.

The tubulationfl is then sealed off by two more.,meta1 surfaces similarto 30 and 3!, and the excess tubulation cut oil? by the knives 36, asillustrated in Figure 6. A suitable socket connection can then beapplied to the lamp. As disclosed in Figur 2, a cylindrical casing 40 ofbrass fits tightly over the base projection 20 after one of theconducting standards 22 has its end bent over between the projectingbase 20 and the metal wall 40.

The overlapping tip ll of this connection is soldered to the outer wallof the cylindrical casing. The other end 42 of the other connectin wire23 extends to a metal contact cap 43 embedded in insulation 44 in anopening at the bottom of the metal casing 40. The metal casing 40 mayhave the projecting lugs 45 for retaining the lamp in its socket untilflashed.

If desired screw threads may be placed in the metal casing 40 if a screwthreaded socket is to be utilized. Other types of socket connections canalso be provided, as illustrated in Figure '7, where one of theconnecting standards 46 passes through the bottom projecting tube I!used for tubulation and then sealed off at 48.

The wire issecured to a metal cap 49 at the top end or the sealed oi!tubulation 41. The other connection or standard 50 passes through thecasing to one side 01 the central tabulation l1 and is attached to aconductive band surrounding the tubulation 41. Various other types ofconnections can obviously be made to the ig-' niting means in theinterior of the lamp.

when photoflash lamps, utilizing an organic plastic as a casing, wereutilized, the heat sometimes concentrated near the plastic casing with aresulting volatilization of some or the or anic constituents of theplastic envelope. These volatile compounds burn in the oxygenatmosphere, thereby reducing the oxygen availabl 'ior buming thealuminum or magnesium metal in the lamp. These volatile organiccompounds would then break down with a resulting heavy deposit of carbonon the inside or the envelope. The deposit of carbon. or course, tendedto reduce the light output or the lamp.

My inside coating or a transparent inorganic material, such as sodiumsilicate, acts as a heat insulator, preventing the burning metal fromcoming into direct contact with the organic plastic material or theenvelope. The complete combustion or the aluminum or magnesium charge ofthe photoflash lamp is, accordingly, permitted with a correspondingincreas in light output. This coating, while preferably sprayed on thesurface, can also be placed thereon by flushing a solution or sodiumsilicate on the surface and then permitting it to dry.

It is apparent that many modifications may be made in my invention and,accordingly, I desire only such limitations to be imposed thereon as isnecessitated by the spirit and scope or the following claims.

I claim:

1. A photoflash lamp casing subject to severe internal explosivepressure in use and comprising a base portion and a bulb portion ortranslucent organic plastic or a thickness to be selfsupporting and aninterlocking joint between said base and bulb portion, the edge or saidbulb portion being compressed within said base portion and therebyobtaining increased retentive grip between the bulb portion and baseportion with increase of pressure within the lamp in excess of externalpressure.

2. A photoflash lamp casing subject to severe internal explosivepressure in use and comprising a translucent plastic bulb portion, and abase portion having a rim overlapping the edge of said bulb portion,said bas portion having an interior peripheral groove therein and thebulb portion having a peripheral bead facing said groove and forming aninterlocking joint therewith and thereby obtaining increased retentivegrip of the interlocking joint with increase or pressure within the lampin excess of external pressure.

3. A photoflash lamp casing subject to severe internal explosivepressure in use and comprising a translucent plastic bulb portion, abase portion having a rim overlapping the edge oi said bulb portion,said base portion having an interior peripheral groove therein and thebulb portion having aperipheral bead facing said groove and forming aninterlocking joint therewith and thereby obtaining increased retentivegrip of the interlocking joint with increase of pressure within the lampin excess 01' external pressure, and cement between and at the exterioror said rim and edge thereby sealing the joint to admissionoi air to thebulb while the internal pressure is less than external pressure.

4. In a lamp provided with a radiation-permeable envelope having a neckor material oi the character or organic plastic depending therefrom, abase secured on said neck and providing space between the bottom or theneck and bottom 01 the base, lead-in support wires for a fllamentextending through the bottom or said base and having flattened areas inthe portion thereof where passing through the plastic material, andpressure-sealed thereat by pressure applied normal to the flattenedareas thereby obtaining intimate and tight sealing engagement of thepisstic on the lead-in wires.

5. In a lamp provided with a radiation-permeable envelope having a neck01' material of the character or organic plastic depending therefrom, abase secured on said neck and providing space between the bottom or theneck and bot tom of the base, lead-in support wires for afllamentextending through the bottom or said base and having flattened areas inthe portion thereof where passing through the plastic material.

the bottom or said neck having nipples thereon I surrounding the saidflattened areas oi the leadin wires, and pressure-sealed thereat bypressure applied normal to the flattened areas thereby obtainingintimate and tight sealing engagement of the plastic on the lead-inwires.

/ RAYMOND LE ROY KREIDIJR.

